An incident light ray hits a plane surface at 20 degrees (hint: remember where the angle is measured from). What is the angle between the incident and reflected rays? So is the answer
20 degrees
or
40 degrees

Atypical jetliner lands at a speed of 146 mi/h and decelerates at the rate of (10.4 mi/h)/s. if the jetliner travels at a constant speed of 146 mi/h for 1.5 s after landing before applying the brakes, what is the total displacement of the jetliner between touchdown on the runway and coming to rest?